Analysis of the Shale Gas Reservoir in the Lower Silurian Longmaxi Formation, Changxin 1 Well, Southeast Sichuan Basin, China
详细信息
- 责任者：Chen Wenling (State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation ; Chengdu University of Technology ; Chengdu 610059 ; China) ; Zhou Wen
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(3)
- 关键词：页岩气 ; shale gas ; 储层性质 ; reservoir properties ; 四川盆地 ; Sichuan Basin
- 页码：p.1073-1086
- 图表：illus., 4 tables, 27 refs.
- 分类号：1003
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The shale thickness in the Longmaxi Formation,Lower Silurian is approximately 147m in Changxin 1 well,Changning structure,southeastern region of the Sichuan Basin.Longmaxi Formation lithofacies include laminated mudstone/shale,laminated lime mudstone/shale,laminated and silty mudstone /shale,alcareous concretions and pyrite band.The bottom 30m of which is organic-rich laminated mudstone /shale,whose quartz,feldspar and pyrite average content is 51.9%,the clay mineral average content is 24.7% and the calcite and dolomite average content is 23.4%,which is similar with the typical American shale reservoirs.The average porosity of Changxin 1well is 5.68% and the average permeability is 5.96×10-3μm2.They are positively correlated.The micropores in the shale observed in the SEM are dominated the minerals intergranular(dissolution) pores,intergranular gaps,intragranular pores,the organic matter micro-pores and micro-fractures.Based on the Mercury intrusion porosimetry,The max of the radius of the pore throat is 33nm,the average is 10nm.The study shows that the development of micro-pores of marine shale gas reservoir in the Longmaxi Formation in Changxin 1 well are controlled by lithology,diagenetic evolution and the characteristic of organic matter.The organic-rich shale porosity is better than the organic-lean shale,silty shale and calcareous mudstone/shale.In the late diagenetic stage,arrangement of clay minerals is changed,the montmorillonite changes to illite,which forms new micro-pores to increase the porosity.TOC is one of the main factors to control the shale gas reservoir in the Longmaxi Formation and also is the important material to provide the storage space to shale gas.
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